New acylated anthocyanins and other flavonoids from the red flowers of Clematis cultivars

Abstract

Six new acylated cyanidin glycosides, cyanidin 3-O-â-(2″-E- caffeoylglucopyranosyl)-(1→2)-O-β-galactopyranoside (1), cyanidin 3-O-β-(2″-E-caffeoylglucopyranosyl)-(1→2)-O-β-(6″- malonylgalactopyranoside) (2), cyanidin 3-O-β-(2″-E- caffeoylglucopyranosyl)- (1→2)-O-β-(6″- succinylgalactopyranoside) (3), cyanidin 3-O-β-(2″-E- caffeoylglucopyranosyl)-(1→2)-O-β-galactopyranoside-3′- O-″- glucuronopyranoside (4), cyanidin 3-O-β-(2″-E- caffeoylglucopyranosyl)-(1→2)-O-β-(6″-malonylgalactopyranoside) -3′-O-β-glucuronopyranoside (5), and cyanidin 3-O-β-(2″-E- feruloylglucopyranosyl)-(1→2)-O-β-(6″-malonylgalactoside) -3′-O-β-glucuronopyranoside (6), were isolated from the red flowers of two Clematis cultivars, 'Niobe'and 'Madame Julia Correvon'. The chemical structures of the isolated anthocyanins were determined by UV, LC-MS, HPLC, TLC, characterization of hydrolysates, and 1H and 13C NMR spectroscopy, including H-H COSY, C-H COSY, HMBC, HMQC and NOESY. The last three anthocyanins were widely distributed in 37 red flower Clematis cultivars. On the other hand, the first three compounds were found only in two cultivars. Five known flavonol glycosides, kaempferol 3-O-glucoside, kaempferol 3-O-rutinoside, quercetin 3-O-galactoside, quercetin 3-O-glucoside and quercetin 3-O-rutinoside, were isolated from the flowers of 'Madame Julia Correvon'.